added extends file

config/initializers/constants.rb

@@ -196,10 +196,6 @@ class Constants
     'text/plain'
   ].freeze
 
-  # Notification types. Should not be freezed, as modules might append to this.
-  NOTIFICATIONS_TYPES = { assignment: 0,
-                          recent_changes: 1,
-                          system_message: 2 }
   # Organization name for default admin user
   DEFAULT_PRIVATE_ORG_NAME = 'My projects'.freeze
 

config/initializers/extends.rb

@@ -0,0 +1,17 @@
+# Extends class holds the arrays for the models enum fields
+# so that can be extended in sub modules.
+
+class Extends
+  # To extend the enum fields in the engine you have to put in
+  # lib/engine_name/engine.rb file as in the example:
+
+  # > initializer 'add_additional enum values to my model' do
+  # >   Extends::MY_ARRAY_OF_ENUM_VALUES.merge!(value1, value2, ....)
+  # > end
+  # >
+
+  # Notification types. Should not be freezed, as modules might append to this.
+  NOTIFICATIONS_TYPES = { assignment: 0,
+                          recent_changes: 1,
+                          system_message: 2 }
+end